Roche’s emicizumab cuts bleed rate by 87% in hemophilia A

The Roche Tower--Courtesy of Taxiarchos228(By Taxiarchos228 (Own work) [FAL], via Wikimedia Commons)

Roche has released a closer look at the data it hopes will propel hemophilia A drug emicizumab to blockbuster status. Emicizumab cut the bleed rate by 87% in patients with inhibitors to factor VIII and aced all the secondary endpoints, leaving lingering concerns about side effects as the main barrier between Roche and big sales.
Investigators gave emicizumab to 35 patients and randomized a further 18 to receive on-demand bypassing agents (BPAs) but no prophylactic treatment. Roche hoped the bispecific antibody would cut the bleed rate by binding to activated factor IX and factor X. This approach is designed to fill the role normally played by factor VII.
Data from the HAVEN-1 trial suggest emicizumab works as hoped. As well as linking emicizumab to an 87% reduction in the bleed rate, the study also found the bispecific antibody cleaned up against the secondary endpoints. Treated spontaneous, joint and target joint bleeds all fell by at least 89%. After a median of 31 weeks, almost two-thirds of patients had suffered no treated bleeds. Only 5% of patients in the control arm were similarly unaffected by bleeds.
Looking at efficacy alone, the data suggest Roche has a shot at putting a dent in Novo Nordisk and Shire’s hemophilia franchises. However, safety concerns could limit uptake of emicizumab.
Those safety concerns ratcheted up in February when news emerged of a patient's who took emicizumab. The patient who died was one of three people taking emicizumab to suffer from thrombotic microangiopathy. Roche has also reported two thromboembolic events.
The patient who died suffered a hemorrhage that doctors treated with a BPA. Roche sees the adverse events as a result of treatment with repeated high doses of on-demand BPAs to treat breakthrough bleeds. The labels of BPAs, namely Novo Nordisk’s NovoSeven and Shire’s Feiba, carry thrombosis warnings. 
Roche’s confidence in the safety of emicizumab has failed to quash concerns the adverse events will stymie uptake of the drug. Jefferies analyst Jeffrey Holford foresees a “protracted launch trajectory due to multiple clinical trial readouts needed to build out the label as well as conservative adoption of this therapy.”
A big reward potentially awaits Roche if it can allay these concerns quickly. Holford predicts peak sales of $5 billion a year for emicizumab.

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